SWEEP FREQUENCY RESPONSE ANALYSIS

Sweep Frequency Response Analysis (SFRA) is a major advance in transformer condition analysis, allowing you to "see" inside transformers and detect even subtle changes in the mechanical structure of the core and windings - without costly detanking.

The standard definition of Frequency Response Analysis (FRA) is the ratio of a steady sinusoidal output from a test object subjected to a steady sinusoidal input. Sweeping through the frequency range of interest gives rise to the S in SFRA, to distinguish it from impulse methods, which estimate the response rather than measure it.

Sweep Frequency Response Analysis (SFRA) is a proven technique for making accurate and repeatable measurements on a transformer. As compared to the "impulse" technique, SFRA is preferred for frequency domain measurements. It covers the full dynamic range and maintains the same energy level for each frequency, providing accurate, consistent results. A high signal-to-noise ratio across the entire 20 Hz to 2 MHz frequency range ensures valid measurements.

The DOBLE instruments M5400 and M5300 send an excitation signal into the transformer and measure the returning signals. Comparing this response to baseline and other results (such as from similar units) allows you to identify deviations and confirm internal mechanical problems, such as:

• Core movement
• Winding deformation and displacement
• Faulty core grounds
• Partial winding collapse
• Hoop buckling
• Broken or loosened clamping structures
• Shorted turns and open windings

Add the DOBLE M5400 or M5300 Sweep Frequency Response Analyzer to your quality-control and maintenance toolkit, as these instruments are the most effective diagnostics tools on the market for detecting mechanical problems in your power transformer!